In co-pending application Ser. No. 07/452,291 now U.S. Pat. No. 5,161,152 entitled "High Speed Synchronous Transmission Line Access Terminal," now U.S. Pat. No. 5,161,152 there is shown a structural configuration of a line shelf which is constructed with a back plane connector array and slots for receiving various plug-in units. The line shelf includes redundant power supplies, line shelf processors, line shelf access units and test access units for remote terminal applications and a channel test unit in lieu of the test access units if the line shelf is used at a central office terminal A total of forty-eight line units are provided in four groups of twelve each.
In order to expand the functionality of the above line shelf to include a fiber-to-the-curb (FTC) application, a new shelf called the optical distribution shelf (ODS) has been developed and is the subject of a separate co-pending patent application entitled "Optical Distribution Shelf for a Remote Terminal of an Optical Fiber Telecommunications Network" being filed under U.S. Ser. No. 07/738,315.
A problem found in developing the FTC product, with only fiber distribution in the remote housing, is that there is no access provided for metallic voice frequency (VF) services at the housing, yet these services are required for craft communications as well as existing line testing architectures.